Embryology - CVS 2 Flashcards
What are the primitive aorta?
The first arteries (the right and primitive aortae) appear in the embryo. Each aorta has a ventral and dorsal part.
How is the aortic sac formed?
The two ventral aortae fuse, then becomes an extension of truncus arteriosus.
Aortic arch branches arise from the aortic sac.
How are the aortic arches formed?
During the 4th and 5th weeks, six pairs of aortic arches are formed from the aortic sac.
These arches unite with the dorsal aortae and give rise to the great arteries of the neck and head.
How do blood vessels develop?
Vasculogenesis - the new formation of a primitive vascular network.
Angiogenesis - the growth of new vessels from pre-existing blood vessels.
What are the adult derivatives of the aortic arches?
1st and 2nd arches - disappear early.
3rd arch - common carotid artery.
4th right arch - right subclavian artery.
4th left arch - aortic arch.
5th arch - disappears.
6th right arch - right pulmonary artery.
6th left arch - left pulmonary artery and ductus arteriosus.
What are aortic arch anomalies?
Most defects of the great arteries arise as a result of persistence of aortic arches that normally regress, or regression of arches that normally shouldn’t.
How can the right subclavian artery cause an anomaly?
Abnormal origin on the left may constrict the trachea and oesophagus.
What is a double aortic arch?
Non-regression of the right aortic arch.
Forms a vascular ring around the trachea and oesophagus, causing difficulty in breathing and swallowing.
What is PDA associated with?
Commonly associated with maternal rubella infection in early pregnancy.
Can be associated with ASD, VSD, and coarctation of aorta.
What is PDA?
The muscular wall fails to contract, causing respiratory distress syndrome and a lack of surfactant in the lungs.
If uncorrected, it may lead to congestive heart failure with increasing age.
What is the coarctation of the aorta?
A congenital condition where the aorta is narrow, usually where the ductus arteriosus inserts. Most common in the aortic arch.
Can be proximal to the ductus arteriosus (preductal) or distal to it (postductal).
How do the embryonic vessels develop into adult vessels?
Vitelline (yolk sac) - gut.
Umbilical (placenta) - internal iliac.
Cardinal (rest of the body) - SVC and IVC.
How does deoxygenated blood circulate before birth?
The right and left umbilical arteries arise from the foetal internal iliac arteries, carrying deoxygenated blood. They move to the placenta for the exchange of gases, nutrients and waste. The placenta acts as the lungs and kidneys for the foetus.
How does oxygenated blood become mixed blood in circulation before birth?
Oxygenated blood from the placenta reaches the foetal IVC via the umbilical vein, mostly bypassing the foetal liver. Near the liver, the umbilical vein divides and forms the hepatic portal vein. Blood in the foetal IVC is mixed.
What is the ductus venosus?
Shunts blood in the left umbilical vein into the IVC. Allows oxygenated blood from the placenta to bypass the liver.
